Fluid powered ultrasonic washing, rinsing, and drying system for a dishwasher

ABSTRACT

A fluid-powered ultrasonic washing, rinsing and drying system for a dishwasher wherein an ultrasonic frequency generator is provided in the form of a cylindrical nozzle located on a centrally disposed tower in the washing compartment. The tower has an axial water pump driven inner detergent water solution feed line and an axial flow air-vapor pump driven outer vapor and compressed air feed line which draws vapor from the compartment and exits it at high velocity from the cylindrical nozzle to reflect off a resonator ring primary surface and a distributor secondary surface in a spherical wave form to the compartment.

United States Patent Jacobs Dec. 17, 1974 [54] FLUID POWERED ULTRASONIC WASHING, 2,980,123 4/1961 Lemelson 134/1 X RINSING, AND DRYING SYSTEM FOR A FOREIGN PATENTS OR APPLICATIONS DISHWASHER 1,322,797 2/1963 France 134/191 James W. Jacobs, Dayton, Ohio General Motors Corporation, Detroit, Mich.

Filed: Aug. 30, 1973 Appl. No.: 392,932

Inventor:

Assignee:

References Cited UNITED STATES PATENTS Primary ExaminerRobert L. Bleutge Attorney, Agent, or Firm-Edward P. Barthel 5 7 ABSTRACT A fluid-powered ultrasonic washing, rinsing and drying system for a dishwasher wherein an ultrasonic frequency generator is provided in the form of a cylindrical nozzle located on a centrally disposed tower in the washing compartment. The tower has an axial water pump driven inner detergent water solution feed line and an axial flow air-vapor pump driven outer vapor and compressed air feed line which draws vapor from the compartment and exits it at high velocity from the cylindrical nozzle to reflect off a resonator ring primary surface and a distributor secondary surface in a spherical wave form to the compartment.

4 Claims, 7 Drawing Figures PATENTED I I V 3 854 998 sum 1 HF 3 .9#*- 110 u 58 I 000000 W FLUID POWERED ULTRASONIC WASHING, RINSING, AND DRYING SYSTEM FOR A DISHWASHER This invention relates to dishwashing machines, and particularly to a dishwasher having a fluid-powered ultrasonic washing system.

It is known to use ultrasonic means for agitating liquid washing solution into vibrations to provide mechanical energy within a dishwashing chamber. It is an object of the present invention to provide a sonic wave generator for a dishwashing machine having a cylindrical nozzle for producing an air-vapor jet flow together with a resonating cavity ring surrounding the cylindrical nozzle which cooperates with liquid distribution means coaxial with the jet flow and displaced axially therefrom.

It is another object of the invention to provide ultrasonic dishwashing machines having an axial flow liquid pump which draws water from the sump and delivers it to upper and lower distributors of an ultrasonic generator together with an axial flow vapor pump which draws vapor from the washing compartment for subsequent heating and delivering it in a compressed state to the ultrasonic generator for exiting from a cylindrical nozzle and for echoing off a primary resonator ring surface and a secondary dome-shaped distributor surface in a spherical wave to the compartment.

These and other objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred forms of the present invention are clearly shown.

In the drawings:

FIG. 1 is a generally schematic representation of a dishwasher incorporating the invention;

FIG. 2 is an enlarged fragmentary vertical sectional view of the distributor head showing the spray means in relation to the sonic generator cylindrical nozzle and resonator ring;

FIG. 3 is a vertical sectional view through the lower portion of the spray tower showing the dual pump assembly;

FIG. 4 is a schematic wiring diagram suitable for use with the dishwasher of this invention;

FIG. 5 is a sequence chart for the disclosed control circuit;

FIG. 6 is a side elevational view partly in section of a modified sonic generator and distributor head for the washing machine; and

FIG. 7 is a horizontal section taken on the lines 7-7 of FIG. 6.

In accordance with this invention and with reference to FIG. 1, a dishwasher 10 having an outer cabinet 11 including a top 12, side panels, one of which is partially indicated at 13; a rear panel 14 and a base panel 16 adapted to include the dishwashing chamber or tub shown generally at 18. The dishwashing chamber is ,a generally box-like receptacle having a depressed bottom defining a sump 20. The dishwashing chamber 18 has an access opening 22 in the front wall thereabove the lower front panel 23 which is closed by a dishwasher door shown generally at 24. The door 24 may be hinged to the side panels of the dishwasher as at 25 and latched in any conventional manner so as adapted to be opened by the handle 26. A water-tight connection between the dishwashing chamber 18 and the door 24 such as gasket 28 may be provided and arranged about the periphery of the opening 22.

The dishwasher includes a machine or motor compartment 30 beneath the sump 20 closed by the cover panel 23 across the front portion on the machine compartment and is supported on bottom panel 16 which defines a toe space at the bottom front of the appliance. The bottom wall 32 of the sump is sloped or tapered to direct fluid within the dishwashing chamber to an opening 34 in one portion of the sump wall. Underlying the opening is a drain-and-recirculate T valve 36 operated by a solenoid 38. Valve 36 is arranged to selectively direct water from the sump to a drain line 40 or to a pump inlet conduit 41.

A conventional timer 42 may be set for a given washing cycle at which point water will be introduced into the sump by means of a fill or supply valve 44. Connected to the sump of the dishwasher, as best shown in FIG. 3, is a vapor and water distributing system including an axial flow liquid pump 46 and an axial flow airvapor pump 47 driven by a motor 48. The outlet 50 of the water pump is connected by means of a vertical inner detergent water solution feed pipe 52 to distributor means 54 with the motor 48 mounted in the vertical position on the motor shaft 56 extending upwardly through a cylindrical opening 58 mounting shaft seal 74 into the pump housing 60 where pump impeller 62 is attached to shaft 56 by means of a cone-shaped bolt 64 and a clamp washer 66. Rotation of the impeller with the T valve 36 in its pump inlet position will cause fluid to be drawn through conduit 41 and impelled to lift upwardly into the detergent water solution feed pipe 52, as shown by the solid line arrows in FIG. 3, to set up a water recirculating action to the pipe 52. The drainage action occurs via conduit 41. When the T valve 36 is in its drain position, fluids in the sump 20 will flow by gravity through it to a suitable drain via conduit 40.

A concentrically conforming outer blower housing is formed around the pump housing 60 for receiving an axial flow blower 72 also mounted on the motor shaft 56 with shaft seal 74 positioned to seal the axial flow pump impeller 62 from the subjacent blower 72.

As seen in FIG. 1, an air-vapor return upstanding duct is included between the rearwardly offset portion 81 of the back wall 15 and the chamber rear wall 82, and communicates with the chamber through an opening 84 in the rear wall thereof an inverted cuplike deflector 86 serving to prevent spray from entering the duct 80. The vapor return duct 80 extends vertically downwardly and thence inwardly beneath the sump wall 32 to an inlet 87 in the axial flow blower housing 70 wherein heated air-vapor, as indicated by the wavy arrows in FIG. 3, is returned to the blower. Heating means in the form of a plurality of electrical resistance heaters 90 are arranged in the lower portion 92 of the air-vapor duct underlying the sump and isolated by wire mesh screens 94 and 96 for heating the returned air-vapor prior to its entry into the axial flow blower housing.

As viewed in FIGS. 1 and 2, a sonic energy generator 100 is supported on the upper end of a central tower or column 102. The tower 102 is shown formed as an integral reduced portion of the blower housing and extends upwardly therefrom through an opening 104 in the concentric raised dome 106 of the sump wall 32, which opening is suitably sealed as by rubber-like seal ring 108. The sonic energy generator 100 includes a lower dish-like plate 110 having central depending hub l 12 supported on a reduced diameter extension 114 of .the tower 102. An upper inverted dish-like plate 116 of the generator is supported by central hub 117 on the inner feed pipe 52 in spaced relation from the lower plate 110 whereby a 360 outwardly flowing cylindrical venturi sectioned nozzle 118 is defined therebetween.

As seen in FIG. 2, the generator upper plate supports an upper cup-shaped water distributor head 120 in concentric fashion thereon for receiving a portion of the water exiting from axial outlet 122 of the water feed pipe 52. A plurality of spray ports 124 are evenly spaced around the upper distributor head 120 for the exiting of the water into the washing chamber. In a like manner, a lower cup-shaped water distributor head 126 is supported in a concentric inverted manner on tower 102 such that its upper open end is sealed against the underside of lower plate 1 10. A radial outlet 128 is provided in feed pipe 52 and extends outwardly through an opening 130 in the tower 102 for the flow of a portion of the water into the lower head 126 and thence, outwardly through spray ports 132 into the washing chamber 18 to direct a water vapor-air mixture over utensil supporting baskets 134 and 136 located above and below the distributor 54.

A resonator ring, shown at 140 in FIGS. 1 and 2, is

positioned in spaced concentric relation to the nozzle 118 such that it is symmetrically located on the horizontal plane which bisects the cylindrical nozzle 118. As seen in FIG. 2, the resonator ring 140 body portion 142 has an inwardly concave-convex cross section forming an inner arcuate primary surface 143, provided with upper and lower outwardly canted flanges 144 and 146, respectively. The resonator ring is supported by a plurality of arcuate support wires extending from the upper plate 116 and secured to the outer surface of upper flange 144 as shown for example by the wire 148 in FIG. 2.

As seen by the wavy arrows in H0. 2, when a water vapor and heated air mixture, compressed in the upwardly converging concentric feed space 150 formed by the inner water feed pipe 52 and outer column 102, is directed into the conoid-shaped space 152 of the sonic energy generator 100, the vapor-air mixture is emitted from the cylindrical nozzle 118 in the form of an ultrasonic fluid jet that impinges on the primary annular curved resonator surface 143. The vapor-air mixture exiting at ultrasonic velocity from the cylindrical nozzle echos off the resonator ring and reflects off the distributor heads in a spherical wave form to mix with the washing liquid from the orifices 124 and 132 for impingement on the utensils in the compartment. The primary surface 143 of the ring is adapted to reflect the air-vapor mixture in both an upwardly and downwardly divergent manner for impinging on the secondary curved surfaces of the dome-shaped upper and lower distributors 120 and 126, respectively to produce high frequency acoustical vibrations or ultrasonic waves in the region between the secondary surfaces 120, 126 and the reflector ring annular surface 143.

In the form shown, the radial distance between the primary reflective surface 143 and the secondary surfaces 120 and 126 of the upper and lower dome-shaped distributors rspectively, is of the order of one wave length. The secondary surfaces, thus, reflect the sonic waves in a divergent manner such that they are distributed over a wide angle within the dishwashing chamber 18 for further reflection off dishes and utensils being cleaned and off the side, top and bottom walls of the chamber.

Referring now to FIG. 4, a control circuit is set forth embodying in a representative fashion the major control concepts of this invention. The circuit includes a domestic household electrical supply indicated by L1 and L2 for energizing the components of the control circuitry including a solenoid winding 158 for actuating the normally closed drain valve 36 by solenoid 38 and a solenoid winding 160 for actuating the water supply fill valve 44. These various components and their respective circuits are actuated by a plurality of timer switches which are cam actuated by a timer shaft 162 driven by a timer motor 164. The control circuit further includes the duct heater and the motor 48 for driving the pumps 46 and 47. A holding circuit for starting the normal wash cycle includes start relay 168 operating start switch 170. The circuit may include a door switch 172 which is closed simultaneously with the closing of the dishwasher door. A push-pull timer switch 174 is utilized for initiating the normal washing cycle thus energizing the timer motor 164. A detergent selector switch plate 176 operating between a pair of contacts 7 and 8 to actuate a heater 178 is used to operate the detergent dispenser 179.

In operation, when the timer push-pull switch 174 is closed, assuming the door switch 172 is also closed, the timer motor 164 is energized to initiate the washing, rinsing and drying cycle. The drain solenoid 158 opens via timer contact 1 to allow any water in the sump to flow by gravity to the drain 34 after which the drain solenoid 158 closes. The fill valve 44 is energized by solenoid via timer contacts 9 to fill the sump with water. Next, the motor 48 is energized through timer contact 4 of by-pass switch 180 and the axial flow liquid pump 46 together with the axial flow vapor pump 47 begin to operate drawing water mixed with detergent (previously dumped into the sump upon closing door 24) from the sump and delivering it to the distributors 120 and 126 in the ultrasonic generator 100. At the same time, the axial flow vapor pump 47 draws vapor (air) from the compartment 18 to the return duct 80 and over the heater 90, now energized via timer contact 2, and delivers the heated and compressed vapor to the ultrasonic generator 100.

Vapor exiting at high velocity from the cylindrical nozzle 118 echoes off the resonator ring primary surface 143 (properly spaced to provide the ultrasonic frequency desired) and reflects off the secondary curved surfaces of the distributors 120 and 126 in a spherical wave form to the washing compartment. The liquid solution is mixed with the vapor at the distributor orifices 124 and 132. The system thus proceeds through the various wash and rinse cycles. In the drying cycle, the drain solenoid 158 is energized allowing the water to flow to the drain whereby only heated vapor is circulated throughout the dishwashing chamber 18.

FlGS. 6 and 7 disclose a modified form of the sonic energy generator 100' wherein a resonator ring is supported on the upper distributor head 120' by means of a plurality of radial support means, such as wires shown at 192, having their outer ends fixedly secured as by welding to the outer surface of the ring 190. The inner ends of the wires 192 are secured to a support bearing 193 located on the vertical axis of the distributor head 120' which enables the ring to drivingly rotate about the principal vertical axis of the ultrasonic generator upper 116' and lower 110' plates by the exiting high velocity vapor-air and water solution.

As seen in FIG. 7, the inner surface of the ring 190 is formed in an arcuate stepped or saw tooth configuration 194 such that the radial dimensions from the cylindrical nozzle 118 to the crests 196 and nodes 198 of the stepped surface 194 together with all intermediate points therebetween thereby providing a range of ultrasonic frequencies having wave lengths that vary from A at the crests 196 to A at the nodes 198. Thus, a bandwidth of ultrasonic frequencies is generated to improve the coupling of the energy to the dishes and utensils being cleaned and the interior of the dishwashing chamber 18 is swept by the resulting rotating field of ultrasonic energy to thereby improve the cleansing, rinsing and drying actions.

It will be noted that the cup-shaped distributor heads 120 and 126' provided with apertures 132 are identical to corresponding parts in FIG. 2. While a recirculating dishwashing system is disclosed, it will be apparent that applicants invention is suitable for a noncirculating or straight through automatic dishwasher system.

The present system for a typical example for a domestic dishwasher would require about 0.5 gallons of water per fill with a vapor-air circulation rate of about 500 cubic feet per minute. It is intended that the ultrasonic operating frequencies within the range of 500 and 100,000 cycles per second is suitable Also the washing liquid could be a water detergent solution to combine with the ultrasonic vapor-air so as to create a fog-like mixture operative to clean the utensils.

While the embodiment of the present invention constitutes a preferred form, it is to be understood that other forms might be adopted.

I claim: I

l. A dishwasher comprising; a casing defining a washing chamber having a sump and an access opening, a plurality of utensil supporting rack means secured to said dishwasher casing, a combination vapor-air blower and liquid supply pump including an inner liquid pump housing and outer vapor blower housing concentrically spaced therefrom so as to extend vertically upwardly from said sump, said inner housing enclosing a liquid circulating impeller and said outer housing enclosing vapor-air impeller, motive means for driving both said impellers, liquid passage means connecting said sump with said inner pump housing, vapor-air passage means connecting said washing chamber with said outer blower housing, means for distributing liquid in said chamber for washing dishes or the like, said liquid distributing means including a vertical column mounted on said blower outer housing and in fluid communication therewith, said column extending upwardly to a central part of said chamber, said column having an ultrasonic generator supported thereon, said generator including a lower dish-shaped plate having a concave surface facing upwardly, and an upper inverted dishshaped plate positioned in concentric spaced relation above said lower plate, whereby a 360 Venturi nozzle opening is provided between the adjacent perimeters of said plates; a vertical liquid supply tube positioned within said column such that its lower end is in communication with said pump inner housing, upper and lower cup-shaped liquid distributor heads having their open ends in sealed contact with the central portion of said upper and lower plates respectively, providing upper and lower liquid distributing cavities; said upper and lower heads concentrically supported on said upper and lower plates respectively, the curved outer surfaces of which form secondary dome-like reflecting surfaces, means for supplying liquid to each of said distributor cavities from said liquid supply tube, each said distributor head having apertures therein for directing liquid spray into said washing chamber, a ring fixedly mounted in outwardly spaced concentric relation with respect to said upper and lower plates such that said ring is symmetrically located with respect to a horizontal plane bisecting said Venturi nozzle, said ring having its inner annular face providing a primary reflecting surface in opposed facing relation with said Venturi nozzle such that ultrasonic vapor-air waves emitted by said Venturi nozzle are reflected from said ring primary surface onto said secondary upper and lower reflecting surfaces whereby ultrasonic vapor-air waves are directed outwardly in conjunction with said liquid spray into said washing chamber for impinging on utensils being cleaned in said racks.

2. A dishwasher comprising; a casing defining a washing chamber having a sump and an access opening, a plurality of utensil supporting rack means secured to said dishwasher casing, a combination vapor-air blower and liquid supply pump including an inner liquid pump housing and outer vapor blower housing concentrically spaced therefrom whereby said housings extend vertically upwardly from said sump, said inner housing enclosing a liquid circulating axial impeller and said outer housing enclosing vapor-air axial impeller, an electric motor having a common shaft for driving both said impellers, liquid passage means connecting said sump with said inner pump housing, a vapor-air return duct extending vertically downwardly along one wall of said chamber and thence inwardly beneath said sump wall connecting said washing chamber with said outer blower housing, heating means positioned in the lower portion of said vapor-air duct, means for distributing liquid in said chamber for washing dishes or the like, said liquid distributing means including a vertical column mounted on said blower outer housing and in fluid communication therewith, said column extending upwardly to a central part of said chamber, said column having an ultrasonic generator supported thereon, said generator including a lower plate member having a concave inner surface facing upwardly, an upper inverted identical plate member positioned in concentric spaced relation above said lower plate member having a concave inner surface facing downwardly, whereby a 360 Venturi nozzle opening is provided between the adjacent perimeters of said plate members; a vertical liquid supply tube positioned within said column, said supply tube having its lower end supported on said pump inner housing, upper and lower cup-shaped water distributor heads having their open ends in sealed contact with the central portion of said upper and lower plates respectively, providing upper and lower liquid distributing cavities; said upper and lower heads concentrically supported in mirror image fashion on said upper and lower plates respectively whereby their curved outer surfaces form secondary upper and lower reflecting surfaces, means for supplying liquid to each of said distributor cavities from said liquid supply tube,

7 each said distributor head having apertures therein for directing liquid spray into said washing chamber, a ring fixedly mounted on and in outwardly spaced concentric relation with respect to said upper and lower plates such that said ring is symmetrically located about a horizontal plane bisecting said Venturi nozzle, said ring having its inner annular face providing a primary refleeting surface in opposed facing relation with said Venturi nozzle such that ultrasonic vapor-air waves emitted by said Venturi nozzle are reflected from said ring primary surface onto said secondary upper and lower reflecting surfaces whereby the ultrasonic vaporair waves are directed outwardly in conjunction with said liquid spray into said washing chamber for impinging on utensils being cleaned in said racks.

3. A dishwasher comprising; a casing defining a washing chamber having a sump and an access opening, a plurality of utensil supporting rack means secured to said dishwasher casing, a combination vapor-air blower and liquid supply pump including an inner liquid pump housing and outer vapor blower housing concentrically spaced therefrom so as to extend vertically upwardly from said sump, said inner housing enclosing a liquid circulating impeller and said outer housing enclosing vapor-air impeller, motive means for driving both said impellers, liquid passage means connecting said sump with said inner pump housing, vapor-air passage means connecting said washing chamber with said outer blower housing, means for distributing liquid in said chamber for washing dishes or the like, said liquid distributing means including a vertical column mounted on said blower outer housing and in fluid communication therewith, said column extending upwardly to a central part of said chamber, said column having an ultrasonic generator supported thereon, said generator including a lower dish-shaped plate and an upper inverted dish-shaped plate positioned in concentric spaced relation above said lower plate, whereby a 360 cylindrical Venturi nozzle opening is provided between the adjacent perimeters of said plates; a vertical liquid supply tube positioned within said column such that its lower end is in communication with said pump inner housing, a water distributor head concentrically supported on said upper plate providing a liquid distributing cavity; said distributor head having a curved outer surface which forms a secondary dome-like ultrasonic reflecting surface, means for supplying liquid to said liquid distributing cavity from said liquid supply tube, said distributor head having apertures therein for directing liquid spray into said washing chamber, a ring rotatably mounted in outwardly spaced concentric relation with respect to said Venturi nozzle such that said ring is symmetrically located about a horizontal plane bisecting said Venturi nozzle, said rings inner annular face formed with a stepped configuration defining primary ultrasonic reflecting surfaces including a plurality of crests and nodes in opposed facing relation with said cylindrical Venturi nozzle, the radial dimensions from said cylindrical Venturi nozzle to said primary stepped reflecting surfaces resulting in a range of ultrasonic vapor-air wave frequencies being reflected from said primary surface onto said secondary dome-like reflecting surface whereby the ultrasonic vapor-air waves are directed outwardly in conjunction with said liquid spray into said washing chamber for impinging on utensils being cleaned in said racks.

4. A dishwasher comprising; a washing chamber having a sump, a utensil supporting rack in said washing chamber, a vapor blower and a liquid pump assembly supported below said sump, motive means for driving said blower and said pump, liquid passage means connecting said sump with said pump, vapor passage means connecting said washing chamber with said blower, means for distributing vapor and liquid in said chamber for washing dishes or the like, said distributing means including a vertical column extending upwardly into said washing chamber, said column having an ultrasonic generator supported thereon, said ultrasonic generator including a 360 Venturi nozzle for distributing vapor therefrom, means for supplying vapor to said Venturi nozzle from said blower through said column, upper and lower liquid distributor heads concentric to said 360 Venturi nozzle and having curved outer surfaces forming vapor reflecting surfaces, means for supplying liquid to each of said distributor heads from said pump through said column, each of said distributor heads having apertures therein for directing liquid into said washing chamber, a reflector ring mounted in outwardly spaced concentric symmetrical relation to said 360 Venturi nozzle, said ring providing a primary reflecting surface in opposed facing relation with said Venturi nozzle such that vapor emitted by said Venturi nozzle is reflected from said primary surface onto said curved outer surfaces of said liquid distributor heads whereby ultrasonic vapor waves are generated and directed outwardly and combined with liquid exiting from said distributor head apertures so as to be directed into said washing chamber for impinging on utensils being cleaned in said rack. 

1. A dishwasher comprising; a casing defining a washing chamber having a sump and an access opening, a plurality of utensil supporting rack means secured to said dishwasher casing, a combination vapor-air blower and liquid supply pump including an inner liquid pump housing and outer vapor blower housing concentrically spaced therefrom so as to extend vertically upwardly from said sump, said inner housing enclosing a liquid circulating impeller and said outer housing enclosing vapor-air impeller, motive means for driving both said impellers, liquid passage means connecting said sump with said inner pump housing, vapor-air passage means connecting said washing chamber with said outer blower housing, means for distributing liquid in said chamber for washing dishes or the like, said liquid distributing means including a vertical column mounted on said blower outer housing and in fluid communication therewith, said column extending upwardly to a central part of said chamber, said column having an ultrasonic generator supported thereon, said generator including a lower dish-shaped plate having a concave surface facing upwardly, and an upper inverted dish-shaped plate positioned in concentric spaced relation above said lower plate, whereby a 360* Venturi nozzle opening is provided between the adjacent perimeters of said plates; a vertical liquid supply tube positioned within said column such that its lower end is in communication with said pump inner housing, upper and lower cupshaped liquid distributor heads having their open ends in sealed contact with the central portion of said upper and lower plates respectively, providing upper and lower liquid distributing cavities; said upper and lower heads concentrically supported on said upper and lower plates respectively, the curved outer surfaces of which form secondary dome-like reflecting surfaces, means for supplying liquid to each of said distributor cavities from said liquid supply tube, each said distributor head having apertures therein for directing liquid spray into said washing chamber, a ring fixedly mounted in outwardly spaced concentric relation with respect to said upper and lower plates such that said ring is symmetrically located with respect to a horizontal plane bisecting said Venturi nozzle, said ring having its inner annular face providing a primary reflecting surface in opposed facing relation with said Venturi nozzle such that ultrasonic vapor-air waves emitted by said Venturi nozzle are reflected from said ring primary surface onto said secondary upper and lower reflecting surfaces whereby ultrasonic vapor-air waves are directed outwardly in conjunction with said liquid spray into said washing chamber for impinging on utensils being cleaned in said racks.
 2. A dishwasher comprising; a casing defining a washing chamber having a sump and an access opening, a plurality of utensil supporting rack means secured to said dishwasher casing, a combination vapor-air blower and liquid supply pump including an inner liquid pump housing and outer vapor blower housing concentrically spaced therefrom whereby said housings extend vertically upwardly from said sump, said inner housing enclosing a liquid circuLating axial impeller and said outer housing enclosing vapor-air axial impeller, an electric motor having a common shaft for driving both said impellers, liquid passage means connecting said sump with said inner pump housing, a vapor-air return duct extending vertically downwardly along one wall of said chamber and thence inwardly beneath said sump wall connecting said washing chamber with said outer blower housing, heating means positioned in the lower portion of said vapor-air duct, means for distributing liquid in said chamber for washing dishes or the like, said liquid distributing means including a vertical column mounted on said blower outer housing and in fluid communication therewith, said column extending upwardly to a central part of said chamber, said column having an ultrasonic generator supported thereon, said generator including a lower plate member having a concave inner surface facing upwardly, an upper inverted identical plate member positioned in concentric spaced relation above said lower plate member having a concave inner surface facing downwardly, whereby a 360* Venturi nozzle opening is provided between the adjacent perimeters of said plate members; a vertical liquid supply tube positioned within said column, said supply tube having its lower end supported on said pump inner housing, upper and lower cup-shaped water distributor heads having their open ends in sealed contact with the central portion of said upper and lower plates respectively, providing upper and lower liquid distributing cavities; said upper and lower heads concentrically supported in mirror image fashion on said upper and lower plates respectively whereby their curved outer surfaces form secondary upper and lower reflecting surfaces, means for supplying liquid to each of said distributor cavities from said liquid supply tube, each said distributor head having apertures therein for directing liquid spray into said washing chamber, a ring fixedly mounted on and in outwardly spaced concentric relation with respect to said upper and lower plates such that said ring is symmetrically located about a horizontal plane bisecting said Venturi nozzle, said ring having its inner annular face providing a primary reflecting surface in opposed facing relation with said Venturi nozzle such that ultrasonic vapor-air waves emitted by said Venturi nozzle are reflected from said ring primary surface onto said secondary upper and lower reflecting surfaces whereby the ultrasonic vapor-air waves are directed outwardly in conjunction with said liquid spray into said washing chamber for impinging on utensils being cleaned in said racks.
 3. A dishwasher comprising; a casing defining a washing chamber having a sump and an access opening, a plurality of utensil supporting rack means secured to said dishwasher casing, a combination vapor-air blower and liquid supply pump including an inner liquid pump housing and outer vapor blower housing concentrically spaced therefrom so as to extend vertically upwardly from said sump, said inner housing enclosing a liquid circulating impeller and said outer housing enclosing vapor-air impeller, motive means for driving both said impellers, liquid passage means connecting said sump with said inner pump housing, vapor-air passage means connecting said washing chamber with said outer blower housing, means for distributing liquid in said chamber for washing dishes or the like, said liquid distributing means including a vertical column mounted on said blower outer housing and in fluid communication therewith, said column extending upwardly to a central part of said chamber, said column having an ultrasonic generator supported thereon, said generator including a lower dish-shaped plate and an upper inverted dish-shaped plate positioned in concentric spaced relation above said lower plate, whereby a 360* cylindrical Venturi nozzle opening is provided between the adjacent perimeters of said plates; a vertical liquid supply tube positioned within saiD column such that its lower end is in communication with said pump inner housing, a water distributor head concentrically supported on said upper plate providing a liquid distributing cavity; said distributor head having a curved outer surface which forms a secondary dome-like ultrasonic reflecting surface, means for supplying liquid to said liquid distributing cavity from said liquid supply tube, said distributor head having apertures therein for directing liquid spray into said washing chamber, a ring rotatably mounted in outwardly spaced concentric relation with respect to said Venturi nozzle such that said ring is symmetrically located about a horizontal plane bisecting said Venturi nozzle, said ring''s inner annular face formed with a stepped configuration defining primary ultrasonic reflecting surfaces including a plurality of crests and nodes in opposed facing relation with said cylindrical Venturi nozzle, the radial dimensions from said cylindrical Venturi nozzle to said primary stepped reflecting surfaces resulting in a range of ultrasonic vapor-air wave frequencies being reflected from said primary surface onto said secondary dome-like reflecting surface whereby the ultrasonic vapor-air waves are directed outwardly in conjunction with said liquid spray into said washing chamber for impinging on utensils being cleaned in said racks.
 4. A dishwasher comprising; a washing chamber having a sump, a utensil supporting rack in said washing chamber, a vapor blower and a liquid pump assembly supported below said sump, motive means for driving said blower and said pump, liquid passage means connecting said sump with said pump, vapor passage means connecting said washing chamber with said blower, means for distributing vapor and liquid in said chamber for washing dishes or the like, said distributing means including a vertical column extending upwardly into said washing chamber, said column having an ultrasonic generator supported thereon, said ultrasonic generator including a 360* Venturi nozzle for distributing vapor therefrom, means for supplying vapor to said Venturi nozzle from said blower through said column, upper and lower liquid distributor heads concentric to said 360* Venturi nozzle and having curved outer surfaces forming vapor reflecting surfaces, means for supplying liquid to each of said distributor heads from said pump through said column, each of said distributor heads having apertures therein for directing liquid into said washing chamber, a reflector ring mounted in outwardly spaced concentric symmetrical relation to said 360* Venturi nozzle, said ring providing a primary reflecting surface in opposed facing relation with said Venturi nozzle such that vapor emitted by said Venturi nozzle is reflected from said primary surface onto said curved outer surfaces of said liquid distributor heads whereby ultrasonic vapor waves are generated and directed outwardly and combined with liquid exiting from said distributor head apertures so as to be directed into said washing chamber for impinging on utensils being cleaned in said rack. 